CRP Tech air inlet bike

CRP Racing, 125cc. Outlined in red, the front air inlet similar to the one produced in WINDFORM.

CRP Technology, an Italian 3D printing and engineering company, has used selective laser sintering (SLS) and its WINDFORM line of materials to deliver a more spacious solution for a Moto3 racing customer.

Wiring in motor racing vehicles continue to become more complex and power units are made up of several parts that need to be integrated into the final assembly. It culminates in a crowded front fork area, which can restrict air flow to the air-box and hinder the engine’s performance. By reverse engineering an original airbox, CRP engineers were able to tinker with the design, before 3D printing a pair of prototypes that would carry the wiring and allow a clear pathway for air to pass through the airbox.

Though the CRP engineers agreed a new design was necessary, they also knew the new model would have to fit the current platform, which meant modification of the existing frame and triple clamps was to be avoided. If the new design could not be supported by the existing platform, testing the on-track advantages and disadvantages would be impossible. Furthermore, engineers would be unable to make a direct comparison between new and old inlet.

Deciding on the method of reverse engineering, CRP scanned the original airbox and assembled it with CAD software. Considering the amount of available space, and the assembly constraints of the current airbox, a new model was created which was longer, and brought the opening up to the front side of the fairing, which would, in theory, provide a direct air flow with less turbulence.

CRP Tech air inlet software

CAD files of the front air inlet

Printing the first prototype in WINDFORM GF 2.0, engineers were able to assess whether the design fitment was correct and suitable for assembly. The selected material brought cost benefits, and would also enable the engineers to perform multiple tests. Testing the prototype, CRP noticed a lack of space available under the lower triple clamp, which would worsen when the bike cornered – often where a race is won and lost.

To solve this issue, CRP would look towards one of its newer WINDFORM products, the WINDFORM RL, a rubber-like composite material, while the second prototype was being developed. WINDFORM RL was bonded to the main structure that was made out of WINDFORM XT 2.0. The concept was to use WINDFORM RL to produce the bottom part of the duct in the fork and triple clam area, before assembling this into the top part, made of WINDFORM XT 2.0. Under breaking conditions, the engineers assumed the front fender could move up and collapse the inlet duct without causing any damage due to the material’s flexibility.

After examining the part, which included bonding tests and evaluation in racing conditions, the engineers discovered the potential for additional benefits by making the ducting flexible in the same area next to the front decks. Maximising the duct volume became particularly important, since the maximum steering actions are only reached when the bike is pushed into the paddock by technical staff, post-race.

CRP Tech air inlet part

Detail of the Front air inlet-bottom part in WINDFORM® RL (flexibility) after testing. The graze in the part was the result of the front fork touching the inlet duct during testing.

When the second prototype was produced, in WINDFORM GF 2.0 but with the view to use WINDFORM RL and XT 2.0 for the final prototype, the engineers noticed some more necessary changes in the front fork area. Firstly, the soft section being too short, meaning the forks could touch the area of the duct near the bonding overlap when steering travel was checked from lock to lock position. And secondly, towards the back of the flexible area, near the airbox, the duct was very close to the front wheel in the maximum braking position.

Through the testing of the second prototype, it was determined the front fender contact area on the duct in the soft part was too large when the rider of the motorcycle braked sharply. The rider was particularly unhappy with this because during hard braking the steering must be free from movements, in case immediate corrections to the trajectory of the bike are required. By reducing the portion that would make contact with the fender, the drag perceived by the rider would be reduced.

The final version of the prototype was printed in two separate parts before being bonded together. WINDFORM XT 2.0 was used to make the top part of the air inlet, while the bottom part was made in WINDFORM RL. In order for the CRP team to get the correct fit for performance, the bottom part was enlarged according to the second round of tests, while WINDOFRM RL was used to provide the part with some flexibility. For the top part, WINDFORM XT 2.0 was utilised to reduce weight of the from and central inlet.

The two SLS parts were bonded after being printed separately. CRP outline that the bonding of the two parts is one of the most important phases of the process, as the right selection of bonding methods and adhesives means an enhanced accuracy and functionality.